Certain BSD-based Telnet clients, including those used on Solaris and SuSE Linux, allow remote malicious Telnet servers to read sensitive environment variables via the NEW-ENVIRON option with a SEND ENV_USERVAR command.

The remote host is running Apple Mac OS X, but lacks Security Update 2006-004.

This security update contains fixes for the following applications :

AFP Server Bluetooth Bom DHCP dyld fetchmail gnuzip ImageIO LaunchServices OpenSSH telnet WebKit

Updated krb5 packages which fix multiple security issues are now available for Red Hat Enterprise Linux 2.1 and 3.

This update has been rated as having critical security impact by the Red Hat Security Response Team.

[Updated 26 Sep 2005] krb5-server packages have been added to this advisory for Red Hat Enterprise Linux 3 WS and Red Hat Enterprise Linux 3 Desktop.

Kerberos is a networked authentication system which uses a trusted third party (a KDC) to authenticate clients and servers to each other.

A double-free flaw was found in the krb5_recvauth() routine which may be triggered by a remote unauthenticated attacker. Although no exploit is currently known to exist, this issue could potentially be exploited to allow arbitrary code execution on a Key Distribution Center (KDC).
The Common Vulnerabilities and Exposures project assigned the name CVE-2005-1689 to this issue.

Daniel Wachdorf discovered a single byte heap overflow in the krb5_unparse_name() function, part of krb5-libs. Sucessful exploitation of this flaw would lead to a denial of service (crash).
To trigger this flaw an attacker would need to have control of a kerberos realm that shares a cross-realm key with the target, making exploitation of this flaw unlikely. (CVE-2005-1175).

Gael Delalleau discovered an information disclosure issue in the way some telnet clients handle messages from a server. An attacker could construct a malicious telnet server that collects information from the environment of any victim who connects to it using the Kerberos-aware telnet client (CVE-2005-0488).

The rcp protocol allows a server to instruct a client to write to arbitrary files outside of the current directory. This could potentially cause a security issue if a user uses the Kerberos-aware rcp to copy files from a malicious server (CVE-2004-0175).

All users of krb5 should update to these erratum packages which contain backported patches to correct these issues. Red Hat would like to thank the MIT Kerberos Development Team for their responsible disclosure of these issues.

Updated telnet packages that fix an information disclosure issue are now available.

This update has been rated as having moderate security impact by the Red Hat Security Response Team.

The telnet package provides a command line telnet client.

Gael Delalleau discovered an information disclosure issue in the way the telnet client handles messages from a server. An attacker could construct a malicious telnet server that collects information from the environment of any victim who connects to it. The Common Vulnerabilities and Exposures project (cve.mitre.org) has assigned the name CVE-2005-0488 to this issue.

Users of telnet should upgrade to this updated package, which contains a backported patch to correct this issue.

A number of vulnerabilities have been corrected in this Kerberos update :

The rcp protocol would allow a server to instruct a client to write to arbitrary files outside of the current directory. The Kerberos-aware rcp could be abused to copy files from a malicious server (CVE-2004-0175).

Gael Delalleau discovered an information disclosure vulnerability in the way some telnet clients handled messages from a server. This could be abused by a malicious telnet server to collect information from the environment of any victim connecting to the server using the Kerberos- aware telnet client (CVE-2005-0488).

Daniel Wachdorf disovered that in error conditions that could occur in response to correctly-formatted client requests, the Kerberos 5 KDC may attempt to free uninitialized memory, which could cause the KDC to crash resulting in a Denial of Service (CVE-2005-1174).

Daniel Wachdorf also discovered a single-byte heap overflow in the krb5_unparse_name() function that could, if successfully exploited, lead to a crash, resulting in a DoS. To trigger this flaw, an attacker would need to have control of a Kerberos realm that shares a cross- realm key with the target (CVE-2005-1175).

Finally, a double-free flaw was discovered in the krb5_recvauth() routine which could be triggered by a remote unauthenticated attacker.
This issue could potentially be exploited to allow for the execution of arbitrary code on a KDC. No exploit is currently known to exist (CVE-2005-1689).

The updated packages have been patched to address this issue and Mandriva urges all users to upgrade to these packages as quickly as possible.

The remote version of Windows contains a flaw the Telnet client that could allow an attacker to read the session variables of users connecting to a rogue telnet server.

ID	Name	Product	Family	Severity
22125	Mac OS X Multiple Vulnerabilities (Security Update 2006-004)	Nessus	MacOS X Local Security Checks	critical
21840	CentOS 3 : krb5 (CESA-2005:562)	Nessus	CentOS Local Security Checks	high
21834	CentOS 3 / 4 : telnet (CESA-2005:504)	Nessus	CentOS Local Security Checks	medium
19201	Mandrake Linux Security Advisory : krb5 (MDKSA-2005:119)	Nessus	Mandriva Local Security Checks	high
18687	RHEL 2.1 / 3 : krb5 (RHSA-2005:562)	Nessus	Red Hat Local Security Checks	high
18501	RHEL 2.1 / 3 / 4 : telnet (RHSA-2005:504)	Nessus	Red Hat Local Security Checks	medium
18486	MS05-033: Vulnerability in Telnet Client Could Allow Information Disclosure (896428)	Nessus	Windows : Microsoft Bulletins	medium

Detections

Analytics

CVE-2005-0488

critical

Tenable Plugins

critical

high

medium

high

high

medium

medium